Hydraulic pedal depressor



Jan. 2, 1934. A, E, WILKQYFF 1,942,368

HYDRAULI C PEDAL DEPRES 50R Filed Oct. 27, 1928 l N V EN TOR.

AzZ/zur .5. T I/zikgfi /-//5 A TTORNEY5 Patented Jan. 2, 1934 FATE o -FicE 1,942,368 HYDRAULIC PEDAL DEPRESSOR Arthur E. Wilkoff, Niles, Ohio, as's'ignor to Youngstown'Steel Car Corporation, a corporation of Ohio Application October 27,

9 Claims.

My invention relates to apparatus designed for use in testing automotive service brakes, and aims to provide for applying and maintaining any desired pressure upon the brakes, and pressure applied to the brake pedal'at the time of making the test.

Heretofore it has been the practice in testing automotive service brakes, to depress the brake pedal, either manually or by means of a mechanical depressor, in order to cause brake resistance on the drums of the wheels of the'car, and the test was made by determining the resistance to turning the wheel caused by a given amount of pedal depression. In making a test it is desirable to determine the actual pressure applied to the brake pedal at the time of making the resistance test, so that all forces applied areof known quantities, and my invention is particularly adapted for enabling a single operator to conduct the test for these purposes.

My device is simple in construction, requires no attention beyond setting in position, and avoids the constant need of an operator to maintain given pressures on the brake pedal during the test.

My invention involves principles and details of construction which may be incorporated in a simple device, such as illustrated'in the accompanying drawing, wherein Fig. 1 is a side elevation of my improved pedal depressor, in position ready for use;

Fig. 2 is a sectional view thereof, and;

Fig. 3 is a detail sectional view illustrating a modified form of actuating means.

The illustrated form of the'invention shown in the drawing, comprises an extensible-member adapted to be positioned between the brake pedal P and a fixed part or abutment, as for instance, the base of a seat S, of an automobile, as shown in Fig. 1. Said member comprises a fiuidohamber or casing 11 in which is mounted oneor more movable pistons or rams 12, which maybe forced out under pressure of the contained fluid 13 to apply a desired amount of pedal depressing pressure to the brake pedal. Suitable means, such as the screw plunger 14,'in'the laterally extending tubular chamber 15, are provided for applying a predetermined pressure to the fluid in the chamber as indicated by the gage 16 or other suitable means, and for maintaining said pressure constant so that there is no need for more than an occasional glance of the operator to this part of the operation during the testing of the brakes, and he is free to give his whole attention to the latter.

1928. Serial No. 315,553

In the preferred embodiment, the fluid chamber is built up of a Y fitting, into the branches of which are screwed pipe sections of desired length, but it may be made in a single piece or built up from other tubular sections, and provided with any suitable end caps 1'7 and packing 18 for holding a supply of oil, air or other fluid under pressure.

Through the opposite capped outer ends, which serve as stuifing boxes, slide the alined piston members 12, which are fitted on their inner ends with 0111) leathers 19, as is'common in hydraulic appliances. The one piston has its outer end fitted with an attachment 20 for detachable locking engagement with the brake pedal P, and the other piston has its outer end fitted with a suitable cushion 21, for engagement with the base of the seat or other fixed part of the vehicle.

The screw-plunger 14 which is mounted'in the extension 15 of the casing 11 is provided' with a piston head 22, fitted with a cup leather like the other pistons. The piston 22 is advantageously of slight length, so as to render it as-li-ght in weight as possible, and is not connected'to the screw plunger. This arrangement prevents the possibility of air entering the fluid chamber should either of the pistons be extended with-- out corresponding actuation of the screw or other pressure applying medium.

In the form of device shown in Figs. 1 and 2, the screw plunger 14 is threaded through the screw stuffing box 23 on the outer end of the extension 15, and is provided with a-handle 24, by means of which the screw maybe rotated so that its'inner end will engage and force the p'iston 2'2 inwardly and transmit pressure through the fluid in the casing to the pistons or rams 12. Or if desired, the'piston 22 may be subjected to pneumatic pressure, through hose connection 25, controlled by a suitable valve 26, as for instance valve of the type commonly used in pneumatic tires, or any other suitable arrangement permitting of subjecting the piston to a required-pressu're'a'nd maintaining saidpressure constant'for a desired time.

Any leakage ofthe oil or'othe rlfliiid'from the chamber 11 "m be supplied throughahcie m the side of the casing closed by a plug 2'7 or other suitable means.

My invention provides a convenient means for 165 depressing the brake pedal, under any pressure at which it is desired to make the brake test, and adjusting or setting the depressor so as to maintain the pressure constant, without the necessity of the continued attention of the operator. The 110 the degree of the depressing force, comprising in invention may readily be adapted to different conditions of use, is easily transported, and contains no parts likely to get out of order.

The invention is not restricted to the details of construction shown in the drawing.

I claim:

1. A pedal depressing device for use in automotive brake testing systems comprising a fluid casing,'oppositely movable elements therein and extending beyond said casing, adapted to be positioned between and for engagement with a brake pedal and a fixed part of the vehicle, means for applying a predetermined fluid pressure against said elements in opposite directions thereby to extend said members in said casing and depress the pedal under a predetermined pressure, and means connected to said casing for measuring the pressure applied to said elements.

2. A brake pedal depressing apparatus arranged to depress a brake pedal and indicate the degree of the depressing force, comprising in combination, a case containing fluid and having two oppositely extending cylinders, a piston in each cylinder, a piston rod extending from each cylinder, one adapted to engage a brake pedal, the

' other adapted to bear against a stationary abutment, a third cylinder extending laterally from the case, a piston in the third cylinder, means ior forcing the third piston inward to cause fluid pressure against the other two pistons and force their oppositely extending rods outward, and a fluid pressure gauge mounted on the case and in communication with the interior thereof.

3. A brake pedal depressing apparatus arranged to depress the brake pedal and indicate combination, a case containing fluid and having two oppositely extending cylinders, a piston in each cylinder and a piston rod extending from ,each cylinder, one rod adapted to engage an automobile brake pedal, the other rod adapted to bear against a stationary part of the automobile, a third cylinder extending from the case at a sharp angle to the two oppositely extending cylinders so as to avoid interference with the cowl surrounding the operating pedals; a piston in the angle cylinder, means for forcing the last named piston inward to cause fluid pressure against the other two pistons and force their oppositely extending rods outward, and a fluid pressure gauge mounted on the case and communicating with the interior thereof.

4. A brake pedal depressing apparatus arranged to depress the brake pedal and indicate the degree of the depressing force, comprising in combination, a case containing fluid and having two oppositely extending cylinders, a piston in each cylinder and a piston rod extending from each cylinder, one rod adapted to engage an automobile brake pedal, the other adapted to bear against a stationary part of the automobile, a

and force their rods outward, and a fluid pressure gauge mounted on the case and in communication with the interior thereof.

5. A brake pedal depressing apparatus as dc flned in claim 4, characterized by the piston in the laterally extending cylinder being free to move inward when not actuated by the screw, to avoid leakage ofair into the cylinders and case when the device is not in use.-

6. A pedal depressing and pressure measuring device for use in automotive brake testing systems, comprising a fluid casing, opposed movablemembers extending into said casing and adapted to be positioned between and for engagement with a brake pedal and a fixed part of the vehicle, means for applying a predetermined hydraulic pressure against said elements in opposite directions, thereby to extend said members in said casing and depress the pedal under predetermined pressure, pressure measuring means connected to said casing for measuring the pressure applied to said elements, and means for maintaining said pressure upon the pedal.

7. A hydraulic brake pedal depressor comprising a fluid chamber having three branches or extensions, power transmitting fluid therein, piston members in said extensions, two of said piston members being movable in opposite directions in opposed extensionsof said chamber and extending therebeyond and adapted to be positioned between andfor engagement with the brake pedal and a fixed abutment of an automobile, means connected with the third extension adapted to apply pressure upon its piston member and means therein comprising a plurality of extensions, two

of which are in axial alinement, movable piston members in said extensions, the piston members in said alined extensions being oppositely disposed and extending beyond said extensions and adapted to be positioned between and for engagement with the brake pedal and a fixed abutment of an automobile, mechanical means mounted within a third extension for applying pressure upon the piston member therein, and means connected with said chamber for measuring the fluid pressure.

9. A hydraulic brake pedal depressor comprising a fluid chamber with a power transmitting fluid therein having a plurality of extensions, two of which are in substantial alinement, movable piston members in said extensions, two of said piston members being in alinement andextending beyond said extensions and adapted to be positioned between and for engagement with the brake pedal and a fixed abutment of an automobile, a manually operable screw device mounted'in a third extension for applying pressure upon the piston member therein, and means connected with said chamber for measuring the, fluid pressure.

ARTHUR E. WILKOFF. 

